Early generation hearing devices were primarily of the Behind-The-Ear (BTE) type, where an externally mounted device was connected by an acoustic tube to a molded shell placed within the ear. With the advancement of component miniaturization, modern hearing devices rarely use this Behind-The-Ear technique, focusing primarily on one of several forms of an In-The-Canal hearing device. Three main types of In-The-Canal hearing devices are routinely offered by audiologists and physicians. In-The-Ear (ITE) devices rest primarily in the concha of the ear and have the disadvantages of being fairly conspicuous to a bystander and relatively bulky to wear. Smaller In-The-Canal (ITC) devices fit partially in the concha and partially in the ear canal and are less visible but still leave a substantial portion of the hearing device exposed. Recently, Completely-In-The-Canal (CIC) hearing devices have come into greater use. As the name implicates, these devices fit deep within the ear canal and are essentially hidden from view from the outside.
In addition to the obvious cosmetic advantages these types of in-the-canal devices provide, they also have several performance advantages that larger, externally mounted devices do not offer. Placing the hearing device deep within the ear canal and proximate to the tympanic membrane (ear drum) improves the frequency response of the device, reduces distortion due to jaw extrusion, reduces the occurrence of the occlusion effect and improves overall sound fidelity.
The shape and structure, or morphology, of the ear canal varies from person to person. Since the morphology of the ear canal varies so greatly from person to person, hearing aid manufacturers and audiologists have traditionally employed custom manufactured devices in order to precisely fit the dimensions of each user's ear canal. This frequently necessitates impressions of the user's ear canal to be taken. The resulting mold is then used to fabricate a rigid hearing device shell. This process is both expensive and time consuming and the resulting rigid device shell does not perform well during the deformations of the ear canal shape that occurs during normal jaw movement. In order to receive a properly fit hearing device, the user typically has to make several trips to the audiologist for reshaping and resizing. Even after the best possible fit is obtained, the rigid shell rarely provides comfortable hearing enhancement at all times.
Flexible earmolds for hearing devices have been considered. See, e.g., U.S. Pat. Nos. 5,979,589 and 7,362,875, which are hereby incorporated by reference in their entirety. However, these traditional earmolds often provide poor ventilation, often forming airtight contact within ear canals. Traditional earmolds may also push earwax into the ear. Also, while such earmolds provide some flexibility in fitting into varying ear canals, they do not provide optimum alignment and adaptability to a wide degree of variations in ear canal shapes.
Therefore, a need exists for improved hearing devices which are able to conform to various ear canals and are comfortable.